I did some TESS searches and looked at MarkMonitor.
I also looked at wikipedia.
My conclusion is that smartwatch and smart watch are generic terms.
Registered trademarks are Rock Smartwatch, Android Smartwatch, etc.
So, if I were you, I would protect SmarteWatch as a mark, before this hot segment heats up even more.
1. Put up a simple placeholder site (weebly.com).
2. Post a drawing and / or description of a generic smartwatch.
3. Make the site title SmarteWatch, with the TM symbol next to it.
This is a common law trademark.
It is not quite as strong as a registered trademark (with the circle R).
But, it is strong, and can be enforced in court, if need be.
It's also free, as opposed to $1000 or more.